Electron tube



y 1960 K. M. STOLL 2,937,307

ELECTRON TUBE Filed Doc. 5, 1957 2 Sheets-Sheet 1 INVENTOR KEN/VETHMSTOLI.

MEM

ATTORNEY K. M. STOLL ELECTRON TUBE- May 17, 1960 2 Sheets-Sheet 2 Filed Dec. 5, 1957 INVENTOR Kf/VA/[M M. STOLL ham ATTORNEY United States Patent.

ELECTRON TUBE Kenneth M..Stoll, Port Allegany, Pa., assignor, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, De'l., a corporation of Delaware Application December 5, 1957, SerialNo. 700,899 5 Claims. ,(Cl. 313-266) This invention relates to electron discharge devices such aselectron tubes and to a method-of producing such devices.

An electron discharge tube of 'thetype adapted to be operated at high voltages must have rugged cathode support rods which will maintain proper positioning.

of the cathode during tube operation. It "is essential that these support rods be constructed and mounted with- Such a distortion *causes 2,937,307 Patented lVla'y' 17,1960

Figs. 1 through '5 illustrateseveral'of the's'teps used in fabricating an electron tube; a

Fig. 6 is a'top view of -the"electrode mouutshown in Fig. .5; and

' Fig. '7 is a partially sectioned plan view of an electron tube constructed in accordance with procedures illustrated in Figs. 1 through 5.

Referring "to the drawings,'an electron tube '11 is shown com-prisingan envelope '13 having a stem 15 hermetically sealed thereto. The "stem is "provided with an exhaust tubulation 17, external-leads 19 and internally disposed stem leads 21. Abase 23 is positioned around the lower portion of the envelope and is formed to provide a'lug '25 which incloses tubulation 17 after it has been tippedoff or sealed. g

A cup-shaped anode 27 is mounted within envelope 13 by means of the hermetical seal between anodetop cap 29 and the dome of the envelope. Theeathode '31 for the .tube, whichmay be of the indirectly or directly heated type, as shown, is positioned relative 'to the anode '27 by means-o'fthe spaced support rods 33 and'35. An

Generally, in the'type of tube described above, the

cathode is supported upon spaced rods which are in turn mounted upon the stem 'of'the tube and held in position relative to one another and to other electrodes by means of insulators. Such a construction is'expensive'to fabricate and it is not adaptable for automatic production.

Due to the number of pre-formed parts which must be made and assembled manually, positioning of the electrodes varies considerably from one mount to another,

and the quality of the tubes so produced is thereby af fected. V

Accordingly, an object of the invention is to reduce the aforementioned disadvantages and to improve the fabrication of electron discharge tubes.

A further objectis to-ruggedize electron tubes and to facilitate adoption of means for consistently mounting the electrodes thereof.

A still further object is to mount the tube elements in a manner to insure proper positioning of the cathode and. to minimize distortion of the elements.

The foregoing objects are achieved in' one aspect of the invention by the provision of an electron tube having an envelope with a stem portion hermetically sealed thereto. A plurality of leads project from the stem to provide the support and electrical connections for the cathode through a coupling with spaced support rods. These leads are arranged so that they are longitudinally spaced from one another and formed to contact each rod on opposite sides thereof. The lead contact positions on a given rod are reversed from the lead contact positions on the other red. That is, the lead farthest from the stem contacting one rod is disposed on the opposite side of the plane intersecting the rods from the lead disposed farthest from the stem contacting the other rod. To aid in the production of a rugged mount and to facilitate automatic mounting procedures, the support rods are formed as the legs of a substantially U-shaped member which is fed into the assembly position and welded or otherwise attached to the stem leads. Subsequently the curved base portion of the U-shaped member is severed or cut-off to prevent the spaced rods from mounting the cathode. V

For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawings in which:

electrostatic shield 36 is shown connected to rod 35 to reduce the electrostatic forces exerted on the cathode during operation of the tube. These rods are *welded or otherwise afiixed to stem leads 21 adjacent stem 15. Also mounted on leads 21 is the getter 37 and an electron shield 39, which serves to protect the stem from electron bombardment when the potential of anode 27 becomes negative relative to cathode 31 during 'tube operation.

'It can be seen that rods 33 and 35 are each supported by a pair of longitudinally spaced stem leads 21 disposed on opposite sides of the rods from one another. Such an arrangement provides a two position-contact for the rods and thereby enhances rigid mounting {of cathode 31. The stem lead 21 which is connected to the getter, in addition to the upper lead which contactsrod 33 serves to support shield 39.

stem 15 which is connected to rod 33' lies on the opposite side of the plane passing through rods from the lead extending farthestfrom stem '15 which contacts rod 35. The leads 21 positioned closer to stem 15 are reversed in a similar manner. arrangement provides vaccurate guide tracks for feeding the rods 'into position, in addition to providing tension after'weldingso thatthere is a tendency for them to turn in opposite directions. This tension minimizes possibilities of shorts between the electrodes while also assuring the proper central positioning of cathode 31 relative to anode 27.

The tube described above may be fabricated in a manner which is adapt-able for automatic production. Referring to Fig. 1, stem 15 is formed by sealing the connected leads 19 and 21 through glass wafer 41. One of the leads may be bent to facilitate welding of getter 37 thereto, or all of the leads may be bent as shown in Fig. 2 with subsequent welding of the getter. Although there is more access to the leads forwelding the getter at this step of the mounting procedure, it is to, be understood that the getter may be mounted at any time prior to the sealing of envelope 15 to wafer41. A substantially U-shaped conductive member 43 is next afiixed to leads 21 as indicated in Fig. 3 by any conventional means such as by welding. Member 43 may be formed at the assembly position, by rotating the rod legs 33 and 35 about base portion 45 and positioning the legs intermediate the appropriate leads 21. Alternatively, member 43 may be preformed so that legs 43 and 45 may be moved longitudinally between leads 21v for axation thereto.

Shield 39 is formed with a central aperture having a diameter larger than the;distance between rods 33 and 35 to prevent contact therewith and shorting of cathode 31. The shield is threaded over U-shaped rod 43 and positioned for welding to leads 21 as shown in Fig. 4. If desired, thhe shield may be mounted at any time prior tothe sealing of envelope .13. with wafer 41.

- Referring to Fig. 5, the curved base portion 45 of member 43 is severed and removed, and cathode 31 is connected or welded to rods 33 and 35. The severing action may occur before or after welding of the cathode. In addition, shield 36 may be afiixed to rod 35 before or after the cathode has been mounted. If a filamentary type cathode is utilized, as shown, the filament wire may be coated with electron emissive material either prior or subsequent to the welding thereof.

Envelope 13 is next threaded over water 41 and sealed thereto to provide an inclosure for the electrodes. The positioning of envelope 13 determines the anode to cathode spacing particularly in a longitudinal direction. During processing of the electrodes, the gases are removed through exhaust tubulation =17. Subsequently, the

getter 37 is flashed, and the tubulation is tipped-off or with automatic production equipment. It provides uniformly fabricated electrode mounts which produce uniform quality. In addition, the formation of a substantially U-shaped member 43, operating in conjunction with its lead contact positions, imparts a stress to leads 33 and 35 after severing base portion 45, which tends to minimize shorts and which provides improved positioning of the cathode relative to the anode.

Although several embodiments of the invention have been'shown and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. An electron discharge device comprising an envelope having a stem portion, a plurality of stem leads upstanding from and supported by said stem portion, an anode, supported in fixed relation thereto, spaced cathode support rods having a longitudinal axis, and a cathode mounted upon said support rods in spaced relation to said anode, at least two of said stemleads being .formed to contact and position each of the support rods, the leads associated with each rod being disposed in ing from and supported by said stem portion, an anode supported in fixed relation thereto, spaced cathode 'support rods having a longitudinal axis, anda cathode mounted upon said support rods in spaced relation to said anode, at least two of said stem leads being formed to contact and position each of the support rods, the leads associated with each rod being disposed on opposite sides of said rod and in longitudinally spaced relationships with one another.

3. An electron discharge device comprising an envelope having a stem portion, a plurality of stem leads upstanding from and supported by the stem portion, an anode supported in fixed relation thereto, two spaced support rods lying in a common plane having a longitudinal axis, a cathode mounted upon said support rods in spaced relation to said anode, at least two of said stem leads being formed to contact and position each of the support rods, the leads associated with each rod being disposed on opposite sides of said rod and longitudinally spaced along the rod relative to said stem portion, the lead associated with one of said rods spaced farthest from said stem portion being disposed on one side of said plane, the'lead associated with other of said rods spaced farthest from said stem being disposed on the opposite side of said plane.

4. In a process of fabricating an electrode mount for an electron discharge device, employing a cathode, the steps comprising forming a stem having stem leads upstanding therefrom, bending a rod to form a member having spaced legs connected by a base portion, affixing the legs of said member to said stem leads, and removing the base portion of said member whereby said spaced legs are formed to provide separate supports for the cathode.

5. In a process of fabricating an electrode mount for an electron discharge device employing a cathode, the steps comprising forming a stem having stem leads upstanding therefrom, bending a rod to form a member having spaced legs connected by a base portion, aflixing the legs to said stern leads, mounting an electron shield formed to circumscribe the legs of said member upon said leads, and removing the basejportion of said member whereby said spaced legs are formed to provide separate supports for the cathode.

References Cited in the file of this patent Diemer June 23, 1953 

